1. Field of the Invention
The present invention relates to an optical measuring device and to an optical measuring device.
2. Description of the Related Art
An optical measuring device of this generic type is known for instance from European Patent Disclosure EP 0 608 209 A2. It includes a measurement graduation, embodied for instance as a linear measurement graduation, and a scanning unit that is displaceable in at least one measurement direction relative to the measurement graduation. In the scanning unit, a light source, at least one scanning grating and a detector arrangement, having a plurality of photoelements, are provided. In the scanning unit, an attenuation structure is disposed. The attenuation structure includes a grating oriented perpendicular to other gratings in the scanning beam path. With the aid of the additional grating, the light intensity that strikes the detector arrangement can be adjusted in a defined manner. Such adjustment of the light intensity striking the detector arrangement may for instance be necessary if standardized opto-ASICs are supposed to be used in the scanning units of different optical measuring devices. In that case, it can happen that the opto-ASIC, optimized for a first category of optical measuring devices, proves not to be optimal for other categories of optical measuring devices. Thus, it is conceivable that the intensity striking the detector arrangement of opto-ASICs is variously high in the various measuring devices. By use of the previously mentioned attenuation structure, embodied as an additional grating- as proposed in EP 0 608 209 A2—the high signal intensity in the detector arrangement can then be attenuated. Because of the different orientation of the additional grating, the actual scanning beam path for generating the displacement-dependent scanning signals remains largely unaffected. However, EP 0 608 209 A2 does not teach how and where this kind of attenuation structure is most suitably disposed in the scanning beam path or in the scanning unit and how the attenuation structure is most advantageously embodied.